<!DOCTYPE html>
<html>

<head>
<meta charset="UTF-8">
<style>
@page {
    size: 400pt 300pt;
    margin: 50pt;
}

body {
    outline: thin solid rgb(0, 0, 0, 0.25);
}

.block {
    position: relative;
    top: 15pt;
    left: 15pt;
    height: 39pt;
    border-top: 1pt solid black;
    background-color: lightblue;
}
</style>
</head>

<body>
    <div class="block"></div>

    <div class="block">
        <div class="block">
            <div class="block"></div>
        </div>
    </div>
</body>

</html>
